`Grand, gloomy and peculiar'

Robert CrossTribune staff reporter

MAMMOTH CAVE NATIONAL PARK,Ky.--The world's biggest hole in the ground--at least by one way of measuring--has been dug right here. It weaves beneath high ridges covered with tulip poplars, beech groves and black oak trees, or it snakes below rolling meadows dimpled with sinkholes. This part of Kentucky is "the Land of 10,000 Sinkholes," a point of pride.

How big is that hole?

How long is a better question. Leading a tour through one relatively short passage in the immense cavern, park ranger Colleen O'Connor asked a bunch of grade school kids what they thought the length might be.

The pupils' estimates ranged from seven miles to three million, which made O'Connor draw back her tall, thin frame in surprise. "I'm hearing so many different answers that I'm just going to tell you," she said.

"I don't know."

Here in Mammoth Cave National Park--and in most national parks--the interpreters usually speak with more assurance. The children, members of a New London, Ohio, science class, regarded O'Connor with stunned silence.

"What I usually tell people is that this cave is 350 miles long, because that's how many miles of it have been discovered," she explained. "But if you come back next year, I'll probably tell you a different number, because we'll find more of this cave. It might wind up being 1,000 miles long."

Even so, the 500,000 annual visitors, out of 2 million to the park itself, who do venture underground seldom see more than a dozen miles of Mammoth Cave--mostly in tours ranging from one to four miles each.

That limitation allows the tour guides to polish their routines. They explain that the cave was formed over millions of years through the erosional efforts of underground rivers fed by water seeping through breaks in the Earth's surface--breaks called sinkholes.

Water needs to work on porous rock to perform this trick. O'Connor seated her Ohio guests on benches in the cave and pointed her flashlight at the ceiling. "The rock up there is limestone," she said in her reedy, schoolmarmish voice. "This rock down here is calcium carbonate, which is a fancy way of saying limestone. These rocks over here are CaCO3, which basically means limestone."

Yes, caves typically are mostly limestone and limestone byproducts. Unfortunately for rock-formation esthetes, most of the known chambers in Mammoth Cave are covered with a particularly water-resistant sandstone bedrock, which permits very little leakage through the ceilings onto the limestone. Therefore, visitors see only a few stalagmites or stalactites, those impressive stone icicles that take shape as calcium builds up around dripping water.

O'Connor was leading the park's major scenic tour that day. It's called Frozen Niagara and ends up in a dramatically lit chamber dripping with so many stalactites that people feel as if they have stepped into a 200-foot cell full of candle drippings. O'Connor's charges had walked slightly less than a mile through comparatively unremarkable tunnels to get there.

"This isn't the most beautiful cave," ranger Bob Cetera conceded one afternoon, "but Frozen Niagara is probably what people come to the cave to see. At the very end of the tour, you see the stalactites and the stalagmites. You don't see them on the Historic Tour, and some people on that one might feel disappointed that they aren't seeing formations.

"Carlsbad, in New Mexico, is known for that beauty. You're seeing formations almost from the beginning. And most other caves are small but well-decorated."

Cetera calls Frozen Niagara and the Historic Tour the park's "bread and butter" attractions. A couple of other Mammoth Cave tours are shortened versions of those two, accommodating people who lack the time or physical capacity for something longer. A few excursions put the participants through grueling cave explorations, and one takes them through a part of the cave with illumination only from the lanterns they carry--just the way cave tourists did in the old days.

Ranger Joe Duvall took charge of a Historic Tour one afternoon, leading a group of 20 from the brown-brick visitor center down a road to a natural opening fitted with a long, descending stairway. This, appropriately enough, is called the Historic Entrance.

A veteran of more than 30 years, Duvall looks trim as a drill sergeant in his tan uniform and Smokey Bear hat. His version of history proved almost as entertaining as a cavern full of stalactites.

First of all, he made it clear that Kentucky cave people--the first exploiters of caves for various purposes--didn't get into the business thinking they could capitalize on the cave's good looks. Even the sightseers who paid to take a peek late in the 19th Century came here mostly for the spookiness of the experience.

The native peoples who first used the cave thousands of years ago took out gypsum and other minerals for a purpose anthropologists have yet to explain. They may have used them for paint, or as a moisture-retainer in their gardens, or as a magic potion or a laxative.

After pioneers "rediscovered" Mammoth Cave 200 years ago, various private owners also did some mining and looked for other profitable uses. In 1842, a Louisville physician installed a small tuberculosis hospital, but the air proved unsuitable. One owner built an underground hotel in the 1830s. It burned down in 1916 and was never replaced. A 19th Century Methodist minister took his congregation into one chamber during extreme July heat, creating what might have been America's first air-conditioned church. Duvall said cave temperatures always hover around 54 degrees.

He also pointed out a scorched area above the natural rock "pulpit," marking the spot where a torch lit the preacher's Bible. Other visitors used torches to smoke their names and initials onto the ceilings--a forbidden practice now, of course.

People sometimes forget that a cave in its natural state has no light at all, so rangers provide frequent reminders. They talk about the bats and their sonar systems, the sightless and colorless fish in the underground streams, the cave crickets that evolved into a lovely shade of blond because they have no need for camouflage.

Human visitors usually see everything with the aid of artfully placed fluorescent and incandescent bulbs, which are turned off behind them as they proceed through the cave. To help them get the true cave experience, tour leaders always pause at some point and extinguish the lights.

Duvall did this for a moment with remarkable effect. At his urging, everyone fell silent and stood there for a moment in the sort of utter darkness only a cave can impose. One almost feels the eyeballs begin to atrophy and senses the onset of panic.

"It's a different world," Duvall said, finally.

He lit a match. Uneven walls and blinking faces reappeared.

"Now," he said, "that quickly tells us we have no methane here. Aren't you glad?" The group replied with nervous chuckles.

Earlier, Duvall had ushered his followers into the area where an entrepreneur in the early 1800s had set up a crude but effective potassium nitrate plant.

"This cave, basically, is a dried-up stream bed," he explained. "When water was here, it pushed along sand and gravel and clay. When the water receded, it left those items deposited on the floor of the cave. We in Kentucky call that dirt."

Duvall explained how nitrate-rich water was pumped out of the cave and then allowed to evaporate, leaving potassium nitrate crystals--or saltpeter."This," said Duvall, "was shipped back East, where Mr. (Eleuthere Irenee) du Pont, a young chemist, added charcoal and sulfur to the saltpeter--to the dirt of Mammoth Cave--and made gunpowder . . . for the war we were fighting with Great Britain. I've forgotten the name of that war, but it was about 1812.

"Some historians say that had it not been for Mammoth Cave, we would have lost that war. And I believe if we had lost that war, we would have lost our independence. So Mammoth Cave played a very vital role in our freedom today.

"The labor for the movement of that dirt was provided by black slaves," Duvall said. "They would not be free for many years, but they were working for our nation's freedom."

The most famous Mammoth Cave slave, Stephen Bishop, worked as a guide. In 1838, he placed a ladder over a previously unbridgeable chasm called Bottomless Pit, clambered fearfully across and called the chamber on the other side Relief Hall.

Bishop explored Mammoth Cave more thoroughly than anyone before and could draw detailed charts of its chambers from memory. He described the mysterious crannies that only he had seen as "grand, gloomy and peculiar." Bishop may have been the first to sense the extraordinary length of Mammoth Cave, and he set the standard for cave guides to come.

His remains are buried in a little cemetery on a planked trail leading from the Mammoth Cave Hotel. This Heritage Trail--an easy walk, wheelchair accessible--offers an introduction to the land and water above the cave. Strollers find the Guides' Cemetery along the way. Buried with Bishop, who died in 1857, are the bones of other guides and a few tuberculosis patients who were unsuccessfully treated in the cave hospital during the 1840s.

Topside, Mammoth Cave shows off a pleasant chunk of Kentucky, particularly along the banks of the winding Green River. Deer and wild turkeys forage among the spindly tree trunks. Wood ducks skitter across the surface, which truly is green.

At two points, vehicles must cross the river on small ferries (no charge), a charming yet efficient way to reach the other side.

A $5 cruise on a small riverboat, the Miss Green River, allows visitors to sample another aspect of the old days, when big riverboats brought tourists down the river from as far away as Evansville, Ind. So Capt. Cecil Ramsey steers and first mate Johnny Hatcher points out the sights: pleasant scenes, where the wildlife roams and green bluffs loom.

Water still eats away the stone under those bluffs. Mammoth Cave dips as much as 360 feet below the hilltops, and under the cave floor, streams--seeking their own level--find the Green River.

Therefore, passengers on the excursion boat, riding that primordial stone-cutter of a river and looking for telltale black holes, must stare upward into the woods if they want to see those obscure openings that allow entry only to the air and the bats.